For sourceruns videos it's done in one of two ways. It's either added in post in a video editor, or using a plugin. I'm not sure which plugin it is, but it's most likely not legal for speedrunning.
https://cdn.discordapp.com/attachments/877143798700986388/877616043386884166/HudLayout_2_1.res
Edit the line that says "Waezone", at line 33, and replace the HudLayout.res in the portal/scripts/ folder. I don't think there's any reason for this to not be valid in runs, but that's up to the mods.
An update has been released for SST that adds the command sst_portal_resetisg. This command removes Item Save Glitch and is to be used in place of restarting the game. This is a temporary solution while a more robust and legitimate one is developed.
The reasoning for allowing this is to make the ne